Chris Martin and Gwyneth Paltrow attend screening

The 41-year-old 'Iron Man' actress and the Coldplay frontman, who have two children, Apple, 10, and Moses, nine, and announced their split in late March after 10 years of marriage, reportedly appeared "like they were still married" at a screening of 'Hector And The Search For Happiness' in East Hampton, New York.

An eyewitness told PEOPLE.com that Gwyneth, who was accompanied to the event by her mother, Blythe Danner, hosted the special evening for her and Chris' long-time friend, Simon Pegg, who stars in the new film and is Apple's godfather.

The source added: "They seemed so comfortable with each other. It was like they were still married."

Another observer said: "I don't know what's going on with them, but they seem really happy."

Chris, who arrived at the event separately, was spotted chatting to his estranged wife and friends, including Simon, as he sat at a table with Blythe, whom he later escorted back to her car.

Simon also praised the former couple for being "so down-to-earth" at the gathering.

The British actor said: "We go back a long way. I've known Chris for 15 years and I was there when they met and they are dear friends. And Chris is the godfather to my daughter, Tilly, as well. They are both so down-to-earth."

Chris, 37, recently admitted there is still "a lot of love" between him and Gwyneth, but insisted they are still separated.